Well, since no one else has answered I'll add a few comments. Apparently a Denon rep has confirmed the fact that their players are a bit spotty with recordable DVD. I've personally tried many brands of disc, both + & - R with the same results. I'd say my Denon is about 95%-98.5% with DVD-Rs from ProDisc; that is to say almost perfect. If I'm watching a burned movie, I'll usually get thru a movie without any glitch. But every so often there's be a little hangup, dropout or skip. Eventually I conceded defeat: after all, if Denon themselves basically says you're just SOL, what can you do?
BTW, I've tried many brands of players, and the Denon isn't unique in that regard. It seems there's either some wiggle room in the recordable spec or someone's not implementing it right. Literally the only brand I've tried that's bombproof with DVD-Rs is Pioneer. I've tried Sony, Toshiba, Sanyo, RCA, Techniqs, Denon, Apex, and a couple I'm probably forgetting now (never tried an Onk- anyone try DVD-R in theirs?).
When I say glitch, it's often minor enough that most people wouldn't notice at all. Sometimes, if you blink you'll miss it. Again, I might get thru 5 burned discs without any problems, it's hard to say.
The Denon I have has never hiccupped with any boughten media, CD, DVD-A, SACD or DVD, nor have I ever had a problem with CD-Rs or CD-RWs.